Abstract : This paper discusses the on-going transformations of the French defense support. We technically define defense support as all the means contributing to the readiness of military forces. The literature in defense economics presents very little analysis of defense support in its different forms. Neither space nor base locations have been deeply analyzed in such a literature. We try to bridge this gap by discussing and defining an original research framework. Considering both economic and spatial perspectives, we present here the preliminary steps of a theoretical framework to understand the on-going changes in defense support activities. This paper focus on the MRO (Maintenance, Repair and Overhaul) processes in the three branches of the French armed forces. Several factors are involved in the organization of defense support and its cost for a country. If some of them are related to economic activities in general (e.g. budget constraint, cost of inputs, nature of the technology), others represent more specific constraints due to the military nature of defense support activities (e.g. strategic choices in location, technology-driven systems, ageing of military platforms, intensification of operations and its consequences for the obsolescence of systems). Considering both economic and spatial leverages, how can the cost of attaining defense capabilities be minimized under the previous constraints? We focus on the array of measures that surround French defense support in MRO since the end of the 1990s. Considering the importance of economic activities related to defense support, this contribution aims at discussing the evolution of defense support and its costs for the State. More precisely with the tools of spatial economics we expect to examine the concept of optimum in the defense system and new type of economic interconnections (e.g. Public Private Partnerships and outsourcing) between military and civilian activities. More broadly speaking, this path of research could help us to better understand the new type of economic interrelations between defense organization and "territory" as a social fabric.